What is considered "twice a week watering"? Can you really only water on 2 days a week or can you, more specifically water each zone 2 times a week across 4 or 6 days?

You can experiment with running 2 zones concurrently providing you have sufficient water pressure and volume to do so.

 

I can only water on Monday and Thursday. I'm not sure if I can run zones concurrently. I guess that's a controller function? I'll research that. I do have fairly strong water pressure, but I doubt it's enough for that sort of double duty. Thanks!

 

Water early in the morning. Do it before the sun comes up and you’ll be fine. Won’t lose much to evaporation, and you’ll let the sun and heat of the day dry the leaf material off well enough to avoid a fair bit of the fungus opportunities.

 

Thanks for the reply. What do you mean by early in the morning? I need to run for ten hours, so 1am to 11am?

Thanks,
Ken

 

Check the ET guide to calculate how many inches you really need. Most likely it is more than 1in/week.

Do an irrigation audit to see if the layout is correct and you do get 0.4in/hr. Check your numbers, because you stated 71min to get an inch and the MP do 0.4in/hr.

 

I do need to get a rain gauge and verify, but each blade of grass is covered by two sprinkler heads. I think I'm getting .8" per hour (.4" x 2 sprinkler heads). Am I off in that logic?

I do like the earlier idea of squashing the zones. I'm researching that.

Apart from that, can anyone comment on whether running the sprinklers at 1am in the summer is problematic? I've spent a fair bit of time trying to figure this out without much luck. Intuition tells me that water evaporates at the same rate when it's 70 degrees whether it's dark or light. If that's true, how does night time watering introduce a risk of fungus when it's hot? Anyone know? Thanks!

 

Just on the off chance it's useful to anyone else, I found and answer from a reasonably credible source. Here in North Texas, a guy named Neil Sperry is considered to be a fairly authoritative source on all things that grow from the ground. Water Conservation Made Easy - Neil Sperry's GARDENS

Water when it’s cool and calm. That’s why many cities require you to water between 6 p.m. and 10 a.m. Water losses to evaporation are lower then. Best time to water if you have an automatic system? Between 2 a.m. and 8 a.m. Watering then lowers the chances of disease. To lessen the effects of wind, use heads and hose-end sprinklers that keep irrigation water at low angles and in fairly large droplets.

Unfortunately there's STILL some ambiguity here, as the article seems focused on gardens, not lawn, but since he's talking about city guidelines and sprinkler systems, I'm making the leap that this advice applies to lawn irrigation.

I still plan to keep my eyes open for a more technical answer on evaporation and lawn disease. If I find anything, I'll update this post.

 

I think you are complicating this, but feel free to keep searching for some more info. There’s plenty here if I recall that someone shared actual numbers. In the grande scheme, it wasn’t something to stress over.


Worry less about evaporation and more about how long the leaf material stays wet. Wet grass for extended periods of time without drying or sun will cause fungus growth. That’s proven.


Look up dew… that also happens and it’s moisture you didn’t bring to the yard from the irrigation. It happens in the middle of the night and early morning. If you water in the evening before bed, then the dew comes around and stays on your grass until noon you raise the chancr of fungus with grass wet for more than half the day.

So pick your poison. Water at night and stay alert to opportunities with the weather and fungus and use preventative measures or push your watering into the early morning hours and have it done around or shortly after sun up.

 

I start at 2/3am bc my back lawn has many zones that need to run for a long time. No issues for me, as the back is what sees sun first in the AM.

 

Ken I feel for you. That’s a lot of turf to water. I don’t have anything scientific to offer but if possible try to have the watering done by 10am. Also, water when it needs it. I know they say 1” per week but a lot of times that’s more water than it needs. I wouldn’t just throw 1” a week at it unless it was telling (showing) me it was thirsty. Good luck!

 

I often think, “It rains at night and nothing bad happens to my lawn.”

 

Are you sure? It does NOT rain at night on my lawn and still SOMETHING BAD happens to my lawn.
That is the problem with fine lawns. You can seemingly do everything “right” and still court problems. Nature and bad luck conspire against us.
Very little is natural about a nice lawn.😱

 

I would water at night as you want and add in a schedule to spray preventative fungus control every 2-3 weeks or more often.
That kind of solves your dilemma.

 

Wow! Thanks for all the replies! I've reached the "acceptance" stage in the five stages of grief and will water at night in the summer.

I did find a few other sources that also suggest night watering isn't particularly risky. One of the sources comes from a college, and the guy in the photo is wearing a lab coat so I think it's legit. I plan to follow the regional watering guidance at "WaterMyYard.org" until I can psych myself up to digest the watering guidance posted here.

Thanks again, all!

 

Hi All. I searched and couldn't find this topic but if I've missed it, feel free to mock me and point me the right way.

I've got around 20,000sf of grass. The builder installed MP Rotators throughout, and each blade of grass (for the most part) is covered by two heads. I've got 15 MP-rotator zones. I'm in North Texas, where summers get HOT.

Google tells me that watering at night will surely kill my grass by disease, and watering in the daytime is a waste of effort due to evaporation.

We are restricted in the summer to twice-a-week watering. The presents me with a math problem. To get 1" of water down per week, each zone needs to run for a total of 75 minutes, or 38 minutes per watering-day. Fifteen zones times 38 minutes each is 570 minutes, or nine and a half hours.

This leads to my two questions:

Is watering at night in this scenario bad? Texas summers are so hot that I'm skeptical that it'll introduce stagnant water diseases, but I recognize that I'm underqualified to make that call in real-life.

Would I be better off with a different layout that covered the grass with less zones?

And one last semi-related question... Sometimes the MP rotators stop spinning, and nothing other than replacement brings them back to life. The streams are strong, and if I reduce the angle, they'll spin (and replacements work fine), so I don't think it's a water pressure issue. Is this just the cost of rolling with these nozzles?

Thanks,
Ken

The MP Rotator is designed as a slow application sprinkler -- very slow application. Designed to put our 0.4"/hour so to get an inch of water on the ground you need nearly three (3) hours! 15 heads running sequentially add up to forty-five (45) hours or darn near two (2) days. Am I reading the specs wrong?

 

The MP Rotator is designed as a slow application sprinkler -- very slow application. Designed to put our 0.4"/hour so to get an inch of water on the ground you need nearly three (3) hours! 15 heads running sequentially add up to forty-five (45) hours or darn near two (2) days. Am I reading the specs wrong?

Each blade of grass is covered by two sprinkler heads, so I think my application rate is .8" per hour. I ordered some of those tiny rain gauges from Amazon, and will formally test that theory later this week.

Not really legible, but here's a sketch up of my layout that I painstakingly cobbled together upon move in. The hand written stuff was done under duress (getting hit with sprinklers). That's my excuse for the sloppiness.

 

If the dew typically sits on your lawn until 10am, then shoving your watering schedule forward to end at 10am sure won't hurt since if there's still dew on the lawn, you aren't losing a lot to evaporation. Done by sun up is a great rule of thumb but sometimes you have toned those rules a bit to get the necessities done. You also may be able to have the sunny zones complete early in the schedule so they dry out faster. Setup the north/west (shaded in early AM) zones to be the last ones completed as they are going to be wet late into the morning anyways.

 

I know for sure St Augustine isn't the best to water at night due to the possibilities of disease. I stick to early moong start times like 4-5am and my lawn is like a fraction of your size.

 

Ken, you can find the answers to your questions through the link below. Long story short - watering after nightfall is best for both water conservation and to avoid disease.

By the way, if you're worried about starting too early in the night, why can't you just run 8 zones one night of the week (304 minutes) and the other 7 the other night of the week? You could start after midnight and get it done done by 5 a.m. two times per week, and you'd also minimize the risk of disease even more.

Landscape Irrigation Management Part 5: Irrigation Time of Day

Discover why early morning or late evening irrigation is best for water conservation and plant health.

hgic.clemson.edu